Calipers and dividers



(No Model.) I

N. MARSH.-

GALIPBRS AND DIVIDBRS.

No. 419,165.l Patented Mar. 81, 1891.

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NELSON MARSH, OF AIWIHERST, MASSACHUSETTS.

CALIPERS AND DIVIDERS.

i SPECIFICATION forming part of Letters Patent No. 449,165, dated March 31, 1891.

Application tiled December 1l, 1890. Serial No. 374,366. (No model.)

-To all whom it may concern:

'Be it known that I, NELSON MARSH, a citizen of the United States, residing at Amherst, in the county of Hampshire and State of Massachusetts, have invented certain new and useful Improvements in Calipers, Dividers, Gages, and other Like Instruments; and I do hereby declare that the following' is a full, clear, and exact description of the same, reference being had to the annexed drawings, making a part of this specification, and to the letters of reference marked thereon.

Figure 1 of the drawings represents a side elevation of my improved calipers partly in section; Fig. 2, a view at right angles to that of Fig. 1; Fig. 8, a detail view showing the arms of the calipers extended; Fig. 4, a detail view of the spring-ring which forms the head to the calipers.

The present invention has relation to certain new and useful improvements in calipers, dividers, gages, and other like instruments or tools, and has for its object toimprove the construction thereof, whereby a more perfect control of the instrument or tool is obtained and the same rendered more eective, as well as possessing superior strength and durability, which objects are attained by the device substantially as shown in the drawings, and hereinafter described and claimed.

In order to better illustrate my invention, I have shown a pair of calipers as one of the many instruments or tools to which the construction constituting the invent-ion is applicable, A representing the arms which in the calipers are bent on acurve, as shown. These arms, however, are differently constructed, depending entirely on the kind of instrument or tool used-as, for instance, a pair of dividers in which the arms would be straight and pointed at their ends.

The arms A at their upper ends have segmental threaded grooves a, in which is seated the lower end of an adjusting-screw B, said screw nicely tting in the grooves and the threads thereof engaging with those in the grooves. These grooves render the engagement of thev threads more perfect, as well as preventing any undue strain thereon in a lateral direction, and enable the arms to be adjusted with a greater nicety. The grooves also enable a much liner screw-thread to be used, as they act as guides for the adjustingscrew and retain it in a true line, and the liability of jamming the threads of the grooves by the screw getting out of line is entirely avoided. Upon the outer edge of the arms A and near their upper ends are grooves b, with which engage shoulders c at the inner extremity or back of open slots d of a split spring-ring C, said ring forming or constituting the head of the instrument or tool. The ring or spring-head C holds the arms or legs A in place and retains the threads of the grooves ct in engagement with those of the adjusting-screw B, while the shoulders c are stationary pivots or joints upon which the arms or legs A swing.

The upper ends of the arms-or legs A extend up through the open slots d of the springhead C, said head acting as atension to prevent any lost motion from wearing of the parts.

The screw B extends down through a hole f in the spring-head C, and is retained in position by asectional nut D, engaging with said screw, the latter having the usual thumb-nut g, by which it may be turned.

As previously stated, the construction above described is applicable to many instruments or tools which have parts requiring adjustment relatively to each other-such as dividers, gages, and the like-and therefor I do not desire to confine myself to any special form or kind of instrument or tool, and also reserve the right to make such changes or modifications in the details of construction as would come within ordinary mechanical skill.

Having now fully described my invention, what I claim as new, and desire to secure by Letters Patent, is-

In an instrument or tool, the combination, with two arms or legs having at their upper ends segmental threaded grooves, of a spring split ring engaging with the ends of the arms or legs, and an adjusting-screw extending down through the band of said ring and engaging the threads ot` the grooves, substantially as and for the purpose set forth.

ln testimony that I claim the above I have hereunto subscribed my name in the presence of two witnesses.

NELSON MARSH.

Witnesses:

E. A. THOMAS, S. I. WHITAKEE. 

